# CVE-2026-6957: Path traversal in Mattermost Legal Hold plugin via unsanitized file name from federated peer allows arbitrary file write.

> CVE-2026-6957: Path traversal in Mattermost Legal Hold plugin via unsanitized file name from federated peer allows arbitrary file write.. CVSS 8.0 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-6957
Last updated: 2026-06-17T11:01:32Z

- Published: 2026-05-27 14:23 UTC · Updated: 2026-06-17 11:01 UTC · Assigner: Mattermost
- CVSS: 8.0 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
- EPSS: 0.30%, 22th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-22

## Description

Mattermost Plugins versions \<=1.1.5 fail to sanitize filenames received from federated peers before using them to construct export destination paths, which allows an administrator of a remote federated Mattermost server to write files to arbitrary locations within the target server's filestore via a malicious filename delivered through the shared-channel attachment sync protocol. Mattermost Advisory ID: MMSA-2026-00659

## Affected vendors and products

- Mattermost: Mattermost

## Tracked companies

- [Mattermost](https://rewindex.com/company/mattermost.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-6957)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-6957)
- [https://mattermost.com/security-updates](https://mattermost.com/security-updates)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-6957 · Markdown: https://rewindex.com/cve/CVE-2026-6957.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-6957 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:09:11.648Z